This invention relates to a refrigerator.
Referring to FIG. 1, the vortex tube device 10 receives a supply of compressed gas through a radial inlet 12 to an annular chamber 14 that surrounds a vortex generator 16. The vortex generator, which may be made of synthetic resin material, has an annular wall 18 that is formed with multiple straight bores 20 lying in a common plane perpendicular to the central axis of the annular wall. Typically, there are 6-12 bores depending on the air volume and pressure. The bore size also depends on air volume and pressure. The goal for a vortex tube is to drop as little air pressure as possible in the chamber, to maximize rotational speed after the chamber. The axes of the bores are tangential to the inner cylindrical wall of the vortex generator. The gas entering the annular chamber 14 at relatively high pressure passes through the bores 20 into the cylindrical vortex chamber 24 bounded by the inner cylindrical surface of the vortex generator. The vortex chamber communicates at one axial end with the interior space of a tube 28 by way of a relatively large circular opening and is limited at its opposite axial end by a wall having a substantially smaller circular opening 30. The tube 28 is partially closed at its opposite end, having apertures 34 adjacent the periphery of the tube and being blocked at the center. The apertures 34 may be provided by passages formed in a throttle valve (not shown) that is threaded into the end of the tube 28. Some gas leaves the vortex chamber 24 by way of the tube 28 and the apertures 34 at the far end of the tube, and some gas is able to escape from the vortex chamber by way of the circular opening 30. Because the gas enters the vortex chamber tangentially at high speed, the flow of gas creates a vortex spinning at a speed of up to about 1,000,000 rpm in the vortex chamber and the path of least resistance for the gas in this vortex is through the larger circular opening. Due to the high velocity of the gas particles entering the vortex chamber 24, the particles pass from the vortex chamber into the tube 28 and travel towards the opposite end of the tube. Some of the gas is able to escape through the apertures 34 and gas that is unable to escape must flow back through the tube 28 and through the vortex generator and leave through the opening 30. Because the gas particles arriving at the far end of the tube have substantial angular momentum, the vortex flow is maintained in the flow back toward the vortex generator and an inner vortex is created within the outer vortex flow from the vortex generator. Because the radius of the inner vortex is much smaller than the radius of the outer vortex, the inner vortex initially rotates at a substantially higher angular velocity than the outer vortex. Ultimately, however, friction between the inner vortex and the outer vortex causes the angular velocity of the inner vortex to decrease so that the two vortices rotate at the same angular velocity and there is no longer a difference in angular velocity. Since the radius of the inner vortex is smaller than the radius of the outer vortex, the linear velocity of a particle in the inner vortex is smaller than the linear velocity of a particle in the outer vortex. Consequently, as the inner vortex is decelerated to the angular velocity of the outer vortex, energy is transferred from the particles of the inner vortex to the particles of the outer vortex and the gas stream that leaves through the apertures 34 is at a higher temperature than the inlet gas and the gas stream that leaves through the opening 30 is at a lower temperature than the inlet gas.
The vortex tube device has found several commercial applications, for example in spot cooling, but is subject to limitation as a refrigerator because only a relatively small proportion of the gas leaves through the opening 30.
The published performance data for one commercially available vortex tube device shows that if inlet air at a temperature of 85° F. and relative humidity 55% is supplied at 120 psig and is discharged to ambient pressure (0 psig), the vortex tube device provides 22 cfm air at 35° F. from the cool outlet and consumes 7,460 watts. It can be shown that the coefficient of performance is 0.14.